- Add sauce ingredients into a bowl and mix together until fully combined. Heat over medium-low heat, stirring to avoid burning. Take off heat when sauce is reduced by half. Set aside to cool.
- Add sushi seasoning to cooked brown rice, mix and sit for 15 mins.
- Add vegetables into a large mixing bowl. Add in ½ cup flour and salt, and toss until coated thoroughly.
- In a separate bowl, prepare the tempura batter by incorporating the remaining plain flour, potato starch and ice water. Then add the batter with vegetable mix, tossing to combine.
- Heat the vegetable oil in a wok. Spooning bits of the vegetable batter into the oil, using a chopstick to shape it into a round form.
- Remove from oil when golden and place on wire rack or drain on paper towel.
- To shape sushi buns, spoon 2-3 tbsp of sushi rice into an egg ring and press to mold into shape. Place sushi buns on heated pan to sear the surface.
- Assemble the burger by adding wasabi, pickled ginger, cucumber and desired amount of sauce before topping off black sesame seeds on top of sushi bun.